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Unread 12-10-2014, 10:47 AM   #1
Brigadier
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Emissions - Broken CEL Bulb

Anyone have any experience with this? My check engine light bulb was on and the bulb "happened" to break. The jeep seems to be running fine otherwise and Im fairly confident that it would pass emissions otherwise. Would the emissions test center still know that the CEL light should be on? Do they hook up to the computer at all on the OBD 1?

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Unread 12-10-2014, 11:28 AM   #2
mike134
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They probably won't hook it up to the computer. They can know the bulb is broken because it will not illuminate when they turn the key to the ON position.

However... they have to know that the 1991 Jeep wrangler even HAS a check engine light. They weren't required until 1996. But the legislation USUALLY mentions that IF it does have a check engine light, then it has to work. This varies widely state to state though.

It really depends on how your state does testing. If it is free, I'd say bring it over and see if they notice/care.

They will most likely do a tailpipe test.

Why not get it fixed so you can get your engine codes out though? new bulb! there aren't that many problems on the wrangler that trigger a full on CEL anyway. Just give us the code and we can lead in the correct direction for repair.
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Unread 12-10-2014, 11:33 AM   #3
Brigadier
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Right on Mike. Thank you. Its $20 for the emissions test but its worth a shot. Ill just play dumb if he asks about it. I'll let you guys know what happens!
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Unread 12-10-2014, 11:48 AM   #4
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If you were in Commifornia, I would GUARAN-DAMN-TEE you that you will fail if that EMISS light does not light up and go off at start up. Ask me how I know. My advice, is to spend 30 minutes and fix the bulb. Fix the issue, and go to the SMOG place once. If you fail, it could lead you down a slippery slope with the end result of you having to spend a grip of cash to get your Jeep back on the road. Playing dumb is for dumb people. Do it right - do it once.

IN FACT... On our 91, when we got it, the idiot light cover was missing completely. I found one from a Jeep parts salvage guy and installed it. Our light on our 91 SHOULD say EMISS but it says CHECK ENG and the jerkasaurus rex at the smog place said he could fail me for not having the correct silk screened light cover.

For those that don't know, I freakin HATE CA emission and CARB idiots. HATe is not strong enough - LOATHE - EMNITY gahhhh!
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Unread 12-10-2014, 11:52 AM   #5
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I hear you Luca. The problem is is that I have temp plates on it that expire on friday. It was throwing a 27 code that I could not figure out how to repair within my means and my mechanical capacity. Ive verified that all the injectors are spraying, all the plugs look good. I dont know what else to do. The bulb would be an easy repair since i was the one who accidentally "broke" it
I just need to get this thing through emissions so i can register it. Like I said, Im confident that it would pass otherwise.
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Unread 12-10-2014, 11:57 AM   #6
mike134
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totally agree with all of that. Why do we trust a 25 year old out of business car company's first mediocre attempt at an emissions warning system when we can do a full emissions test on the tail pipe in 5 minutes?

its just stupid legislation... most of the law makers don't know anything about cars and emissions. The ones that do have been briefed by our very "honest" friends of the automotive manufacturing and repair industry lobbies.
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Unread 12-10-2014, 11:59 AM   #7
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27 is Misfire at the Injector

Here's what you need to do:

1. Replace the bulb
2. Remove the ground from the battery for 20 seconds to clear the code from the ECM
3. Remove the injector connectors and clean the contacts using a plastic-safe solvent like a throttle body cleaner NOT brake Cleaner. Make sure that they are completely dry and contaminant free. You may want to put a dab of Dielectric grease in there too - can't hurt.
4. run the jeep for 30-45 minutes and see if the code comes back.
5. if it does, you need to buy or get a Jeep Field Service Manual
6. Use an OHM meter and check the wires for each injector to make sure theres no break that's causing this. Make repairs per FSM
6. if wires are good, you need to verify the actual inectors are good. Make repairs/replace as needed.
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Unread 12-10-2014, 11:59 AM   #8
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If it is actually missfiring, then it won't pass if you do a tailpipe test. You'll have to repair it anyway. You also may be at risk of destroying the catalytic converter if you wait too long to take care of it.

What have you tried so far?
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Unread 12-10-2014, 12:17 PM   #9
Brigadier
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Thanks Luuca and Mike.
What I have done so far is to disconnect battery to try to clear codes. I have also, whith the jeep running, disconnected the connector to each injector individually and each one made the engine idle rough which indicates to me that they are spraying. I also pulled each plug to look for any fouling. Each time I try to clear the codes by disconnecting the battery, the CEL come right back on within 3 seconds of starting it.
I have not done any testing with an ohm meter because im not really sure how to use one and I dont have one.
The first time I did all this, the light went off the next day for about 3 days then came back on. I tried to duplicate what I did the first time to see if it would go off again buit it did not. I do have a FSM that Dank was kind enough to send my way.
Is it possible the even though the injectors are working that they would throw a code? Are injectors either good or bad or is there somewhere in between?
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Unread 12-10-2014, 12:33 PM   #10
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Since it sounds like you just purchased the vehicle, have you gone through the basic used car maintenance items that you should change right away?

Since it sounds like it happens a lot, but intermittantly, I would make sure everything is up to date before breaking out the multimeter on the fuel injectors (still clean and grease the contacts like Luuca suggests as it is very easy!). The following can contribute to missfiring:
1.) Check compression first. You can borrow a compression gauge from autozone for free, you just have to leave a deposit. This will indicate whether your repair will be cheap or costly (time or money, pick one)
2.) New champion copper core plugs (no platinum!). They are about $2 each pre gapped.
3.) Spark plug wires (choose your favorite flavor of price and quality: anywhere from $20-100)
4.) new distributor cap (~$10?)
5.) Fuel filter ($7)
6.) Air filter ($10)
7.) Change the oil and oil filter. (~$20)
8.) Use the LOWEST octane rating you can without pinging. For your engine, this is probably the lowest available. It will burn more easily.
9.) Check for vacuum leaks. Buy some carb cleaner at autozone. with the engine running at idle, spray it on all of the vacuum lines. a change in engine RPM indicates a leak ($4)

Even if something else is the actual CAUSE of the missfire, working on the above may be enough to get you over the border between "not efficient" and "misfiring"

Just FYI: Unrelated to your missfire, but also necessary on a new used vehicle:
1.) Make sure the brakes are good and the lines are not rusted
2.) Change the brake fluid by using a turkey baster to suck it out of the reservoir and put in new DOT-3
3.) change the clutch fluid (turkey baster again)
4.) change the transmission fluid
5.) change the differential fluid
6.) change the serpentine belt
7.) grease all zerk points
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Unread 12-10-2014, 12:34 PM   #11
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Quote:
Originally Posted by Brigadier View Post
Thanks Luuca and Mike.
What I have done so far is to disconnect battery to try to clear codes. I have also, whith the jeep running, disconnected the connector to each injector individually and each one made the engine idle rough which indicates to me that they are spraying. I also pulled each plug to look for any fouling. Each time I try to clear the codes by disconnecting the battery, the CEL come right back on within 3 seconds of starting it.
I have not done any testing with an ohm meter because im not really sure how to use one and I dont have one.
The first time I did all this, the light went off the next day for about 3 days then came back on. I tried to duplicate what I did the first time to see if it would go off again buit it did not. I do have a FSM that Dank was kind enough to send my way.
Is it possible the even though the injectors are working that they would throw a code? Are injectors either good or bad or is there somewhere in between?
An intermittent issue is most likely a wire that is broken within the sheathing and causing issues - that's why I suggested checking the continuity of the wires first. You can throw a grip of money at injectors, but it won't fix a wiring issue. It's not that they aren't spraying, an injector misfire is firing at the wrong time. This can be caused by a faulty wire or perhaps a bad CPS? Need to ask QUE...
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Unread 12-10-2014, 12:54 PM   #12
mike134
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Also, get yourself a multimeter and learn to use it! they are very cheap (~$10, you don't need a fancy one to work on cars) and it's an important life skill, especially in old car ownership!!! We can walk you through how to operate it. It is very easy once you get going.

Test for resistance:
Turn the meter to resistance mode. Touch the test leads to various wires. The meter will tell you the resistance between the wires.
There could be anything in between: a light bulb, a resistor, a coil, just wire, or maybe the wires never connect. A multimeter helps you find out...

Test for continuity:
Do the same as the resistance test except put the multimeter into "continuity mode". It is the same thing, but beeps instead of giving you a reading. This way you don't have to look at the screen.

Test for Voltage:
Put the multimeter in "voltage" mode and touch the leads to any two wires. It will tell you the voltage between the points. Not sure which wire is +12volt powered? use a multimeter to find out!
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Unread 12-10-2014, 01:17 PM   #13
Brigadier
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Thanks all. I appreciate the advice. I actually bought the jeep in 2008 and have done all things that you have recommended since, except the compression test, tranny and diff fluid. Ive heard to leave the tranny fluid alone as I do not know if it was regularly changed and that draining the old fluid and adding fresh might mess things up.
I have replaced all brake lines and calipers as well.
I think, like you guys are saying, it comes down to getting a multimeter.
Sorry if im annoyingly ignorant about how to use one but if I wanted to do the resistance test at the connector for the injector, there are 2 contacts there. am I taking each point of the tester and making contact with each connector individually to get the reading? The resistance should be 0 if done correctly, right?
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Unread 12-10-2014, 01:17 PM   #14
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Luuca, what is a CPS? sorry. ____ position sensor?
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Unread 12-10-2014, 01:29 PM   #15
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Quote:
Originally Posted by Brigadier View Post
Luuca, what is a CPS? sorry. ____ position sensor?
http://www.quadratec.com/jeep-replac...yj-senders.php
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